Single intramuscular dose toxicokinetics of manganese in broiler chicks

Aim: Manganese (Mn) produces neurobehavioral toxicity in various animal species including the young chicks. The present study examines toxicokinetics of Mn in 7-10-day old chicks after an intramuscular injection at 20 mg/kg. Materials and Methods: Samples of the blood, whole brain, liver and kidney were obtained from chicks (5/each time period) at 0 time (base-line) and then at times between 0.17 to 4 h. The concentrations of Mn in the plasma and tissues were determined by atomic absorption spectrometry. Toxicokinetic parameters of Mn were calculated from the mean metal concentrations in the plasma by a non-compartmental analysis using a Windows-based computer program. Results: Injection of Mn significantly increased the metal levels in the plasma, whole brain, liver and kidney of the chicks when compared to respective base-line control values at times 0.17 to 4 h after the injection (with the exception at 2 and 4 h in the brain). The highest concentration of Mn in the plasma and the whole brain appeared one h after the injection, whereas those of the liver and kidney appeared 4 h post-injection. The concentrations of Mn in the plasma ranged between 0.43 to 1.2 µg/ml within 0.17 to 4 h. Those of the whole brain, liver and kidney were 0.11– 0.46, 6.3–15 and 5.3–22.9 µg/g, respectively. The elimination half-life of Mn was 3.02 h with steady state volume of distribution 24.34 L/kg and total body clearances of 4.78 L/h/kg. The mean residence time of Mn was 5.09 h and its area under the plasma concentration-time curve (0- ) was 4.18 µg.h/ml. The elimination half-life of Mn from the brain was 3.12 h with an elimination rate constant of 0.22 h-1. Conclusion: The data suggest that Mn is well absorbed and rapidly distributed after an intramuscular administration in chicks and further support the reported neurobehavioral toxic effects of the metal which are observed within one h after treatment.


Introduction
effects of Mn might be associated with the differential accumulation of the metal in different organ systems Manganese (Mn) is known to be a neurotoxicant of the body [16,18].For example, the neurochemical because of high industrial exposure level in man [1][2][3].and neurobehavioral changes induced by Mn could be The neurotoxicity of Mn has been reproduced and correlated with the differential accumulation of the characterized in various animal species including metal in different regions of the brain [6,20].Plasma, mainly rats and mice [4][5][6][7][8] with few studies in the bone and tissue levels of Mn are additionally used as avian species [9,10].The neurobehavioral effects of diagnostic or biomarker endpoints of exposure [21][22][23].

Mn in man and animals include disturbances of locomotor
The kinetic behavior of Mn has been described in activity and alteration of cognitive behaviors [3,8,11several animal species with wide range of tissue 13].A recent study also described a potential neurodistributions [14,16,18,21].In chicks, Mn administoxicity model of Mn in broiler chicks [10].
tration at 10 to 100 mg/kg, intramuscularly (i.m.)The toxicokinetic and pharmacokinetic aspects produced high levels of the metal in the plasma, brain, of Mn and its tissue distribution are critical points for liver and kidney [10].Further, Mn administrations at evaluating the toxicity and potential harmful effects of 5, 10 and 20 mg/kg, i.m. were found to alter the the metal [14 -17].Such information are important in locomotor activity and other behavioral performance the risk assessment of the metal [17][18][19].The toxic in 7-14 days old broiler chicks [10].However, the toxicokinetics of Mn are not known in chicks which concentration of Mn was determined using atomic could be used as an animal model of neurotoxicity absorption spectrometry (Novaa 350, Germany) with induced by the metal.The purpose of the present study UV-visible lamp and air-acetylene burner.was to examine toxicokinetics of Mn administered at To reduce individual variations in the plasma 20 mg/kg, i.m. in broiler young chicks.concentrations of Mn, means of plasma concentrations of Mn at each sampling time (0.17-4 h) were used to

Materials and Methods
calculate the toxicokinetic parameters by a non-One-day-old broiler chicks of both sexes compartmental analysis [26,27] using a Windowsobtained from a local hatchery were housed at room based computer program [28].The toxicokinetic temperature of 32°C to 35°C with constant lighting, variables included in the calculations were: area under and floor litter consisted of wood shavings.Water and plasma concentration-time curve (AUC ), area under 0feed were available ad libitum.We performed the the moment curve (AUMC ) from time zero to 0toxicokinetic experiment on 45 chicks when they infinity, elimination half-life (t ), elimination rate (MRT=AUMC/AUC) and total clearance (CL= proper attention and care were given to the chicks used Dose/AUC).Furthermore, using a semi log paper, the in this study.
t and k of brain Mn were calculated from Mn We prepared the injectable solution of Mn at 20 and then including the rest of the values until 4 h after Avishkar, India) in unionized distilled water.The the injection.volume of administration was at 5 ml/kg, i.m.The The differences of Mn concentrations in the choice of this dosage was based on our previous study plasma and tissues were statistically analyzed by in which Mn was found to induce behavioral changes analysis of variance followed by the least significant in chicks [10].Blood samples (1-2 ml) were collected from chicks (5/each sampling time) by jugular vein difference test [29].The level of significance was at p < bleeding into heparinized test tubes [24] at 0 time 0.05.(base-line) and then at times of 0.17, 0.33, 0.50, 0.75, Results 1, 1.50, 2 and 4 h after Mn administration.Thereafter, the chicks were euthanized by cervical dislocation to Injection of Mn at the dose rate of 20 mg/kg, i.m. obtain the whole brain, liver and kidneys.Plasma was significantly and variably increased the metal levels in separated from erythrocytes by centrifugation of the plasma, whole brain, liver and kidney of the chicks blood samples at 3000 rpm (Centurion, U.K.) for 15 when compared to respective base-line (0 time) minutes.Plasma and tissue samples were stored at control values at times 0.17 to 4 h after the injection -18ºC pending Mn determination within 48 h.The (with the exception at 2 and 4 h in the brain), (Table 1).plasma and tissue samples were digested in 65% nitric The highest concentration of Mn in the plasma and the acid with 24 h incubation at 70ºC [25].The whole brain appeared one h after the injection, whereas those of the liver and kidney appeared 4 h followed by the kidney and the heart at 2 h following post-injection (Table 1).The concentrations of Mn in an intravenous injection of MnCl [30].Appearance of 2 the plasma ranged between 0.43 to 1.2 µg/ml within Mn in the liver and kidney at high concentrations 0.17 to 4 h (Table 1).Those of the whole brain, liver reflects the metabolic and excretory pathways of the and kidney were 0.11-0.46,6.3-15 and 5.3-22.9µg/g, metal within 4 h [14, 30,31].The pattern of Mn respectively (Table 1).accumulation in the brain which is the target organ for The toxicokinetic parameters of Mn calculated the induction of neurobehavioral changes, depends on from the mean Mn concentrations in the plasma at the chemical formulation of the metal and its route of times 0.17 to 4 h in chicks are shown in Table 2.The administration [6,20].Mn readily enters the brain of elimination half-life of Mn was 3.02 h with steady younger animals compared to adults [32][33][34].This state volume of distribution 24.34 L/kg and total body favors the use of young chicks for monitoring the clearance of 4.78 L/h/kg.The mean residence time of neurotoxic effect of Mn.Mn enters the brain through Mn was 5.09 h and its area under the plasma blood capillaries or by influx into the cerebrospinal concentration-time curve (0-alpha) was 4.18 µg.h/ml.fluid and across the choroid plexus [35,36].Injection Other related toxicokinetic parameters are also listed of radioactive Mn into the blood circulation results in table 2. The elimination half-life of Mn from the within one h in the accumulation of the metal in the brain was 3.12 h with an elimination rate constant of choroid plexus [37].Generally, increased plasma and -1 0.22 h .

Discussion
The toxicokinetic parameters of the present Manganese is widely distributed into various study suggest that Mn is well absorbed and distributed organs of the body and the metal burden correlates in the body of the chicks with a V of 24.34 L/kg and ss with toxic effects seen in the tissues [14][15][16][17][18]21]. High eliminated relatively within a day (CL 4.78 L/h/kg and levels of Mn are also attained in the plasma, brain, t 3.02).V is a reliable estimate of volume of 1/2 ss liver and kidney of chicks following the injection of distribution, since it is calculated independent of the k el the metal at doses ranged between 10-100 mg/kg, i.m. [26,27].Increased levels of tissue Mn burden after [10].The findings of the present study are the first systemic administration are in support of its high systemic toxicokinetic report of Mn in young chicks volume of distribution [14,16,18,21,30].However, following its injection at 20 mg/kg, i.m.This dosage of Mn is almost completely eliminated from the body Mn was reported to alter general locomotor activity of within 5 days in rats [14, 30,31].The reported the chicks with indications of central depressant action elimination half-life of Mn in rats is 4.56 h [14].In our [10].The appearance of Mn in the plasma and the study it was 3.02 h.It should be expected that tissues especially in the brain within one h correlates differences in the toxicokinetics of Mn would exist with the behavioral changes reported in chicks within among various laboratory animal species.The one h too [10].The Cmax and Tmax values indicate variations in the kinetic parameters of Mn across various that Mn is relatively rapidly absorbed into the systemic animal species could be attributed to the differences in circulation of the chicks.High concentrations of Mn the dosage and its form, chemical formulation, route of occurred in the kidney followed by the liver and the administration and species variation [6,14,16,18,20, brain.In rats, Mn highly accumulates in the liver supervised dosing regimen as well as data analysis, Submitted to Arch.Indus.Hyg.Toxicol.
shared in statistical analysis and drafted the 11.Shukakidze, A., Lazriev, I. and Mitagvariya, N. manuscript in English.All authors read and approved (2003).Behavioral impairments in acute and chronic manganese poisoning in white rats.Neurosci.Behav.
the final manuscript.

Table - 1
. Manganese concentrations in the plasma (µg/ml) and tissues (µg/g) of chicks after a single intramuscular administration at a dose of 20 mg/kg body weight Values are mean ± SE of 5 chicks/each sampling time.*Significantly different (except those with the superscript letter a) from respective concentrations between 0.17 to 4 h after the Mn injection, p< 0.05.
Behavioral effects of acute manganese chloride administration in chickens.Biol.Trace.Elem.Res., MAZ executed the experiments, shared in statistical 110: 265-274.analysis and shared in drafting the manuscript.FKM 10.Al-Zubaidy, M.H.I. and Mohammad, F.K. (2012).conceptualized the study, designed the experiment, Potential chick model of acute manganese neurotoxicity.